Selenium supplement, often selenized yeast, are currently the subject of intense study owing to their potential preventive effects against cancer. However, fundamental knowledge of the yeast’s metabolism is required for metabolic engineering biosynthetic production of potent Se-species.
A method for Se/S metabolite speciation in yeast using SCX separation and PEMMS (parallel elemental and molecular mass spectrometry) is described. Samples were taken directly from the fermentor, quenched to instantaneously stop metabolism, followed by extraction of intracellular metabolites for the most accurate determination of metabolites present. Selenium metabolites were detected by simultaneous ICP-MS and ESI-MS/MS while targeted sulphur species were determined by ESI-MS/MS.